Impact clutches



April 20, 1965 K. G. KARDEN IMPACT CLUTGHES Filed April 2, 1962 2Sheets-Sheet 1 INVENTOR.

April 1965 K. s. KARDEN 3,179,219

IMPACT GLUTCHES Filed. April 2, 1962v 2 Sheets-Sheet 2 United StatesPatent C Sweden Filed Apr. 2, 1962, er. No. 154,913 13 Claims. (Cl,192-3ti5) This invention relates to improvements in power operatedimpact tools such as wrenches for tightening or loosening nuts or boltsby power, and more particularly to a reversible impact clutch utilisedin such impact tools for clutching and declutching the hammer member andthe anvil member and for producing rotary blows to the anvil member.

It is a general object of the present invention to provide an improvedimpact clutch for power operated tools which is characterizedparticularly by its simple and compact construction. A more specificobject of the invention is to provide an improved impact clutch forpower operated tools in which for simplicity of operation the clutchingmovement of the impacting clutch member is controlled by a positive camaction while the declutching movement is performed by means of a spring.A further more specific object of the invention is to provide animproved impact clutch of the foregoing character in which the springfor safeguarding declutching movement is. a torsion spring arranged in asimple manner for effective operation over a long operable life andoperable for rotation in both clockwise and counterclockwise directions.

The above and other objects of the come obvious from the followingdescription and from the accompanying drawings in which an embodiment ofthe invention is illustrated by way of example. it should be understoodthat this embodiment is only illustrative of the invention and thatvarious modifications may be made within the scope of the claims withoutdeparting from the scope of the invention.

In the drawings FIG. 1 shows a longitudinal sectional i .view of animpact tool incorporating an impact clutch mechanism embodying theinvention. FIG. 2 is a transverse sectional view taken on the line 2-2in 1. FIG. 3 is a transverse sectional view on the line 3--3 in FIG. 1and showing the impact clutch at the moment of impact. FIG. 4 is a rear.View and section substantially on the line 4 i in FIG. 1. FIG. 5 is aperspective view of a torsion spring incorporated in the impact clutchmechanism of FIG. 1. FIG. 6 is a transverse sectional view correspondingto FIG. 3 but showing the impact clutch mechanism in declutchingposition immediately after impact. FIG. 7 is a transverse sectional viewcorresponding to FIG. 6 but showing the impact clutch in one of itsnormal drive positions with the impact dog ready for riding over one ofthe cam ridges of the anvil member. FIG. 8 is a transverse sectionalview corresponding to FIG. 7 but showing the impact dog in an angularposition past said one cam ridge. FIG. 9 shows a transverse sectionalview corresponding to FIG. 8 but showing the impact dog in the other ofits drive positions ready for riding over the other cam ridge of theanvil member. FIG. 10 shows a transverse sectional view taken on theline lt'i1ll in FIG. 1 during rotation of the impact clutch in onedirection with the impact dog in a position corresponding to FIG. 7.FIG. 11, finally, shows a transverse sectional view corresponding toFIG. 10 but illustrating rotation in the reverse direction.

The power operated impact tool illustrated in FIG. 1 incorporates animpact clutch according to the present invention and comprises a rearhousing 2% having a handle portion 21 and a front housing 22. The fronthousing 22 encloses the impact clutch proper and is proinvention willbeice vided with a central opening 23 at its forward end through whichan anvil member 25 protrudes. The anvil member 25 is supported by a ballbearing 24 carried inside of and by the front housing 22. I11 order toprevent intrusion of dirt into the front housing 22 a ring seal 26 isprovided around the opening 23 and tightens against the anvil member 25.t

Disposed within the rear housing 26 is a reversible rotary motor,preferably as shown a pneumatic motor including a rotor or drivingmember 29 carrying radial vanes or blades 3i slidably supported withinsuitable grooves formed in the rotor. Through the medium of the vanes23% the driving member is driven by compressed air admitted to the motorin a conventional manner, preferably through the handle portion 21 andunder control of a trigger valve, not shown, and the usual reversingvalve 28. The constructional features of the motor per se form no partof the present invention and may be carried out in any suitableconventional manner.

The driving member 253 has an axial bore 31 therethrough and issupported in the rear housing 2t) at its opposite ends by ball bearings32 and 33. The forward end of the driving member 29 extends through theball bearing 32 and is formed with parallel splines 34, FIG. 4, on itsprotruding mantle portion. The front end of the anvil member 25 carriesa polygonal end portion 35 for receiving and carrying various removabletools, such as a socket wrench, not shown, which fits on the end portion35'. Adjacent the ball bearing 24 the anvil member 25 h s a cylindricalcollar 36 resting axially against said ball bearing 24 by means of ashoulder 37 and preventing outward axial movement of the anvil member25. Behind the collar 36 the anvil member 25 forms a cam portion 35 ofsubstantially cylindrical configuration but provided with a pair ofaxially extending spaced apart cam ridges 39 and 4d. The cam ridges 39,dill are provided with radially disposed opposite impact receiving faces41 and 42, respectively, of which one, 41, is turned to receive impactsin clockwise direction, when looking from the rear housing 20 forwardly,while the other, is turned to receive impacts in counterclockwisedirection. The faces 41, 42 are arcuate and formed by an axial partiallycylindrical recess 43 formed in the cam portion 38 along an axisparallel to the axis of rotation of the anvil member 25. At its rearmostportion the anvil member 25 forms a slightly reduced cylindrical bearingportion 44.

A hammer mass 4-5 is arranged coaxially around the anvil member 25 andextends from the collar portion 36 thereof to the rear. The hammer mass45 :is journalled by means of cylindrical bearing portions 46 and 47 onthe collar 36 and the cylindrical bearing portion 44, respectively, forrelative rotation with respect to the anvil member 25. The hammer mass45 preferably is of oval shape and is provided with a central bore 48therein surrounding the cam portion 38 and allowing free rotation of thecam portion 3% and the cam ridges 39, 4d in the bore 43. Adjacent thebearing portion 47 there is provided in the hammer mass 45 a shoulder 49cooperating with the rear face Sit of the anvil member 25 for preventingforward displacement of the hammer mass 45 on the anvil member 2d. Bymeans of a central bore 51 the rear portion of the hammer mass 45 issupported on the protruding end of the driving member 29. In order toform a driving connection the bore 51 is provided with longitudinallyextending grooves 52 which receive the splines 34 of the driving member29. The grooves 52 are somewhat broader in circumferential directionthan the corresponding splines 34, whereby a slight circumferential playor lost motion is created in the driving connection between the drivingmember 29 and the hammer mass 45 for a purpose to be explained furtheron. An axial bore having a radius equal to the radius of the recess 43of the anvil member 25 extends in parallel relation with the axis of thebore 48 and forms a partially cylindrical recess 53 in the hammer masswhich recess 53 faces the cam portion 38 of the anvil member.

The recess 53 receives pivotally therein an impact transmitting dog 54which is journalled in said recess by means of a partially cylindricalrear bearing portion 55 thereon. The main portion of the impact dog 54extending over the rear end of the anvil member 25 has a crescent shapedcross section and the dog 54- faces the cam portion 38 with the concaverecess 56 defining the shorter arc of the crescent shaped cross section.The concave recess 56 merges into the rear bearing portion 55 by a pairof spaced apart edges 57. The concave recess 56 is provided in order toenable the impact dog 54 to rotate past and ride over the cam ridges 59,45. When the impact dog 54 occupies a symmetric position with respect tothe longer axis of symmetry of the cross section of the hammer mass45'both its edges 57 protrude inside of the bore 48 of the hammer mass.The rear portion 53 of the impact dog 54 is fully cylindrical and isjournalled in a corresponding fully cylindrical rear part of the boredefining the recess 53. Adjacent and at opposite sides of the impact dog54 the rear face of the hammer mass 45 forms abutments 59, FIG. 4-. Onthe rear portion 53 of the impact dog 54 there are providedcorresponding angularly offset abutments 6t) cooperating with theabutments and defining the maximum swing of the impact dog 54 in bothdirections.

The rear portion 58 has a forwardly directed surface 61 which has formedthereon an axially and forwardly protruding pin 62 adjacent theperiphery of the rear portion 53 and lying in the plane of symmetry ofthe concave recessed portion 56 of the impact dog 54. The rear end ofthe hammer mass 45 rests against the inner ring of the ball bearing 32while the impact dog 54 is kept in place axially between the outer ringof the ball bearing 32 and an end surface 63 provided in the hammer mass45.

The rotor or driving member 29 carries at its splined end a pair ofdiametrically opposed projections 64, FIG. 10, each aligned with one ofthe splines 3 In the axial bore 31 of the driving member 29 is insertedan elongated torsion spring 66 having a rectangular cross section andbeing bent in hair pin fashion. The ends of the torsion spring 66 arebent at right angles and form shanks 67 and 68 extending in a transverseplane with respect to the axis of the spring 66 with the longer sides ofthe rectangular cross section of the shanks 67, 68 in parallel relationto said plane. The arrangement of the spring 66 is such that when thespring 66 is inserted in the axial bore 31 the shanks 67, 63 willprotrude radially between the rear face 50 of the anvil member 25 andthe forward end of the driving member 25, the shanks 67, 68 extendingalongside each other and embracing under a certain precompression ortwisting of the torsion spring 66 opposed abutments on one of theprojections 64 on the driving member 29 and diametrically opposedportions or abutments of the pin 62 on the impact dog 54, FIG. 10.

In considering the operation of the tool illustrated in the figures, letit be assumed that a bolt to be run down and tightened by the tool has aright hand thread. With the reversing valve 23 set in the correctposition the motor will rotate in a clockwise direction, when viewedfrom the rear housing 26 forwardly, as soon as the operator, havingseized the tool by the handle 21, has positioned the socket wrench, notshown, carried by the end portion 35 over the bolt head and has startedthe fluid motor by pressing the trigger, not shown. Assuming the variousparts of the impact clutch mechanism to be in the positions shown inFIGS. and 7, the driving member 29 rotating in the direction of thearrows rotates the hammer mass 45 together with the impact dog 54!-through direct engagement between the splines 34 and the grooves i 52.As long as the bolt to be tightened rotates with comparative case, asduring the running down period, the mantle surface of the concave recess56 on the impact dog 54 will engage the ridge 39 of the anvil member asviewed in FIG. 7 and will remain in this clutching position owing to thepin 62 being kept firmly between the shanks 6'7 and 63 of the torsionspring 66 in a position slightly offset in the direction of the arrow,FIG. 10, with respect to the central plane extending through the axis ofrotation of the hammer mass 45 and the pivotal axis of the impact dog54. Such angularly offset position of the pin 62 is defined by thedriving engagement between the splines 34 and the grooves 52 in thehammer mass and causes the impact dog to occupy the driving position 1of FIG. 7 with the trailing edge 57 of the impact dog 54 inside of thecylindrical central bore 48 and the leading edge 57 outside of said bore48. The impact dog 54 and the anvil member 25 will remain in engagementso that the bolt is rotated constantly until it is run down and theresistance to rotation increases above some predetermined value.

When the resistance to rotation of the anvil member 25 exceeds saidpredetermined value, the driving member 29 and the hammer mass 4-5 forcethe impact dog 54 to follow the rotation of the hammer mass 45. As aresult the mantle surface of the concave recess 56 is forced to slideover the ridge 39 causing pivotal movement of the impact dog 54 on itsaxis against the action of the torsion spring 66, which by its shank 68opposes the pivotal movement imposed by the passage over the cam ridge39. As soon as the trailing edge 57 of the impact dog has passed theridge 35, FIG. 8, the spring shank 68 immediately urges the pin 62 backto its relative position of FIG. 10 and the trailing edge 57 is againpivoted inside of the cylindrical central bore 48. The driving member 29now quickly accelerates the hammer mass 45 by rotating it around the nowstationary anvil member 25 until the mantle surface of the concaverecess 56 and the trailing edge 57 of the impact dog forcefully runagainst the cam ridge of the cam portion 38, FIG. 9. Against the actionof the spring shank 68 the pin 62 together with the impact dog 54 is nowpivoted in a manner to bring the leading edge 57 of the impact dog 54inside of the cylindrical central bore 48 while the trailing edge 57 ispivoted and accelerated radially away from the ridge 40, whereupon atthe next moment the hammer mass delivers an impact against the recessedportion 43 of the cam ridge 59 by means of the rear bearing portionadjacent the leading edge 5'7 of the impact dog 54-, FIG. 3.

Rebound of the impact dog upon impact creates a force distribution whichenables the shank 68 'of the torsion spring 66 to force the pin 62 backto its normal drive position, FIG. 6, which brings the leading edge 57of the impact dog 54 outside of the cylindrical central bore 48 whilethe trailing edge 57 is brought inside of said bore. Immediatelythereupon the continued rotation of the driving member 29 and the hammermass 45 brings the impact dog back to its normal drive position, FIG. 7.The hammer mass 45, having delivered by means of the dog 54 a rotationalblow to the anvil member 25, continues now rotation of the bolt to betightened until, again, the cammmg force exerted by the cam ridge 39 onthe impact dog 54 overcomes the force of the torsion spring 66 exertedby its shanks 68, whereupon the impact dog again overrides the cam ridge39 and repeats the impact cycle. The position of the impact dog 54 inFIG. 9 may also be occupied during running down of the nut. The firstimpact which with increased resistance to rotation follows'upon suchdrive position will obviously be a weak one because of the angularnearness of the impact position. The powerful blow received by theportions of the impact dog adjacent the trailing edge 57 after fullacceleration from the position of FIG. 6 or FIG. 7 to the position ofFIG. 9 is prevented from rocking the impact dog 54 and its pin 62 toofar against the action of the spring shank 63 by s-,i 79,21 e

means of the abutments 6t on the rear end 53 of the impact dog 54. Theseab'u t'ments 6% will be arrested by the cooperating abutments 5d on thehammer mass 45 as soon as the cam action of the cam ridge 40 and theinertial forces caused by the blow have rocked the leading edge of theimpact dog 54 to the proper depth into the cylindrical central bore 58for the impact, FIG. 3.

The operation of the impact clutch in the reverse direction is, owing tothe symmetry of the impacting and camming portions of the impact dog 54and the symmetry of the cam ridges 39, 40 and of the recess 43 on thecam portion 38, identical with operation in clockwise direction. Ofcourse impacting now occurs against the surface 42 of the cylindricalrecess 43 adjacent the ridge 44 while the cam ridge 39 now in its turnacts as a cam for positively rocking and accelerating the impact dog 54into clutching position. As seen in FIG. 11 the driving member 29 whendriving in the reverse direction or the direction of the arrow moves bymeans of the projection 64 and the spring shanks 67, 63 the pin 62 to anangular position offset in the direction of rotation with respect to thecentral plane through the axis of rotation of the hammer mass 45 and thepivotal axis of the impact dog 54-. Obviously the pin 62 has now tocounteract the spring action of the shank 67 of the torsion spring 56during the rocking movement of the impact dog 54 into clutching orimpact position as well as during overriding of the cam ridge 46. In thedriving position of FIG. 11 the displacement of the pin 62 in thedirection of rotation is attained by the circumferential play or lostmotion in the drive connection between the splines 34 and the broadgrooves 52, the width of which is calculated to give a play resulting ina suitable angle of attack of. the trailing edge portions of the impactdog and movement of the leading edge to a position outside of thecentral bore &8. The diametrically opposed double arrangement of theprojections 64 is provided for creating alternative positions duringassembly of the impact clutch mechanism parts. Each projection 64-, whenstraddled by the shanks 67, 68 of the torsion spring 66, forms opposedabutments for the spring shanks, of which one abutment always holds oneshank of the spring stationary While the other abutment forms an endstop for the movement of the other spring shank when performing returnof the pin 62 to normal drive position.

By providing an axial hole 69 through the anvil member 25 the spring 66may alternatively be mounted in the hole 69 of the anvil member 25. Formaking possible easy rotation of the spring with respect to the anvilmember 25 in such arrangement there may be journalled in the hole 6? atube, not shown, into which the spring 66 may be inserted.

The impact clutch embodiment above described and illustrated in thedrawings should only be considered as an example and the invention maybe modified in several different ways within the scope of the followingclaims.

What I claim is:

1. A11 impact clutch comprising a rotatable anvil member, a rotatablehammer mass coaxially supported with respect to said anvil member,rotatable driving means for said hammer mass, an impact dog pivotallymounted on said hammer mass for rotation therewith and movable relativethereto in clutching and declutching direction about an axis offset frombut parallel with the axis of rotation of said anvil member, cam meansbetween said anvil member and said dog for positively pivoting the dogin the clutching direction, and a torsion spring extending axially ofsaid clutch, said torsion spring being rotatable with said hammer massfor engaging and pivoting said impact dog in the declutching direction.

2. An impact clutch comprising a rotatable anvil memher, a rotatablehammer mass coaxially supported with respect to said anvil member, arotatable driving member, a drive connection incorporating some degreeof play for providing a constantly engaged direct drive between saiddriving member and said hammer mass except for said play, an impactdogpivotally mounted on said hamaxis offset from but parallel with the axisof rotation of i said anvil member, cam means between said anvil memberand said dog for positively pivoting said dog in the clutchingdirection, and spring means rotatable by and with said hammer mass forengaging and pivoting said impact dog in the declutching direction.

3. An impact clutch comprising a rotatable anvil member, a rotatablehammer mass coaxially supported with respect to said anvil member,rotatable driving means for said hammer mass coaxiaily supported withrespect to said hammer mass, an impact dog pivotally mounted on saidhammer mass for rotation therewith and movable relative thereto inclutching and declutching direction about an axis offset from butparallel with the axis of rotation of said anvil member, a firstabutment on said impact dog intermediate the pivotal axis of said impactdog and the axis of rotation of said hammer mass, a second abutment onsaid driving means adjacent said first abutment, cam means between saidanvil member and said dog for positively pivoting said dog in theclutching direction, and spring means extending between said first andsaid second abutments and in engagement therewith for pivoting saidimpact dog in the declutching direction.

4. A reversible impact clutch comprising a rotatable anvil member, arotatable hammer mass coaxially supported with respect to said anvilmember, a rotatable driving member coaxially supported with respect tosaid hammer mass, a drive connection incorporating some degree of playfor providing a constantly engaged direct drive between said drivingmember and said hammer mass except for said play, an impact dogpivotally mounted on said hammer mass for rotation therewith and movablerelative thereto in clutching and declutching direction about an axisoffset from but parallel with the axis of rotation of said anvil member,an extension on said impact dog forming a first pair of opposed abutmentsurfaces intermediate the pivotal axis of said impact dog and the axisof rotation of said hammer mass, an extension on said driving memberadjacent said extension on said impact dog forming a second pair ofabutment surfaces, cam means between said anvil member and said dog forpositively pivoting said dog in the clutching direction, and a torsionspring extending between said first pair and second pair of abutmentsurfaces for engaging and pivoting said impact dog in the declutchingdirection.

5. An impact clutch as set forth in claim 4 in which the ends of saidtorsion spring are provided with laterally protruding shanks extendingin parallel relation to a transverse plane extending with respect to theaxis of said spring and spaced from each other with said first andsecond pair of opposed abutment surfaces therebetween.

6. An impact clutch comprising a rotatable anvil memher, a rotatablehammer mass coaxially supported with respect to said anvil member, arotatable driving member coaxially supported with respect to said hammermass, a drive connection directly between said driving member and saidhammer mass, an impact dog pivotally mounted on said hammer mass forrotation therewith and movable relative thereto in clutching anddeclutching direction about an axis oilset from but parallel with theaxis of rotation of said anvil member, cam means between said anvilmember and said dog for positively pivoting said dog in the clutchingdirection, and a torsion spring oriented coaxially with said anvilmember and said driving member and arranged between said driving memberand said impact dog for pivoting said impact dog in the declutchingdirection.

7. An impact clutch as set forth in claim 6 in which said torsion springis concentric with said driving member.

8. An impact clutch as set forth in claim 6 in which said torsion springis concentric with said anvil member.

9. An impact clutch comprising a rotatable anvil memher, a rotatablehammer mass coaxially supported with respect to said anvil member, arotatable driving member coaxially supported with respect to said hammermass, a drive connection directly between said driving member and saidhammer mass, a partially cylindrical axial recess in said hammer massfacing said anvil member, an impact transmitting dog having a partialcylindrical rear bearing portion thereon, said dog being journalled bysaid bearing portion in said hammer mass recess and supported thereinfor movement in clutching and declutching direction, a recessed frontportion on said impact dog facing the anvil member and merging into saidrear portion by a pair of spaced apart edges, cam means between saidanvil member and one of said edges for pivoting said other edge inclutching direction, and a torsion spring oriented coaxially with saidanvil member and said driv ing member and arranged between said drivingmember and said impact dog for pivoting said impact dog in thedeclutching direction.

10. A reversible impact clutch comprising a rotatable anvil member, arotatable hammer mass coaxially supported with respect to said anvilmember, a rotatable driving member coaxially supported with respect tosaid hammer mass, a drive connection incorporating some degree of playfor providing a constantly engaged direct drive between said drivingmember and said hammer mass except for said play a partially cylindricalaxial recess in said hammer mass facing said anvil member, an impacttransmitting dog having a partially cylindrical rear bearing portionthereon, said dog being journalled by said bearing portion in saidhammer mass recess and supported therein for movement in clutching anddeclutching direction, a recessed front portion on said impact dogfacing the anvil member and merging into said rear portion by a pair ofspaced apart edges, a pin on said impact dog intermediate the pivotalaxis of said impact dog and the axis of rotation of said hammer massforming a first pair of opposed abutment surfaces, at forwardlyextending projection on said driving member adjacent said pin forming asecond pair of opposed abutment surfaces, cam means between said anvilmember and one of said edges for pivoting said other edge in clutchingdirection, and a torsion spring ex tending between said first and secondpair of abutments for pivoting said impact dog in the declutchingdirection. 11. An impact clutch as set forth in claim 10 in which theends of said torsion spring form laterally parallel to a transverseplane through the axis of said spring and spaced from each other withprotruding shanks extending in said first pair and second pair ofopposed abutment surfaces disposed therebetween.

12. In an impact clutch apparatus of the character de scribed having areversible motor with a rotatable driving member extending therefrom, arotatable anvil member c0- axially supported with'respect to saiddriving member and a rotatable hammer mass coaxially supported withrespect to said anvil member, the combination which comprises a drivingconnection incorporating some degree of play for providing a constantlyengaged direct drive between said driving member and said hammer massexcept for said play, an impact dog pivotaliy mounted in said hammermass about an axis offset from but parallel with the axis of rotation ofsaid anvil member in a clutching and a declutching direction, a pinextending from said impact dog intermediate the pivotal axis thereof andthe axis of said hammer mass forming a pair of opposed abutmentsurfaces, cam means disposed and operative between said anvil member andthe trailing edge of said impact dog for positively pivoting the leadingedge of said impact dog in a clutching direction, and spring meansrotatable with said driving member and extending between said drivingmember and said opposed abutment surfaces for moving said trailing edgeof said impact dog into the path of said cam means for drivingengagement and for pivoting said impact dog in a declutching direction.

13. Apparatus as described in claim 12 in which said spring meanscomprises a torsion spring coaxially disposed in said driving member,and laterally protruding shanks extending in parallel to a transverseplane ex tending through the axis of said spring from the end thereofwith said opposed abutment surfaces disposed therebetween.

References Cited by the Examiner UNITED STATES PATENTS 2,219,883 10/40Amtsberg 19230.5 2,343,596 3/44 Van Sittert et al. 19230.5 2,768,54610/56 Amtsberg l9230.5

DAVID J. WILLIAMOWSKY, Primary Examiner.

THOMAS J. HICKEY, Examiner.

1. AN IMPACT CLUTCH COMPRISING A ROTATABLE ANVIL MEMBER, A ROTATABLEHAMMER MASS COAXIALLY SUPPORTED WITH RESPECT TO SAID ANVIL MEMBER,ROTATABLE DRIVING MEANS FOR SAID HAMMER MASS, AN IMPACT DOG PIVOTALLYMEANS FOR SAID HAMMER MASS FOR ROTATION THEREWITH AND MOVABLE RELATIVETHERETO IN CLUTCHING AND DECLUTCHING DIRECTION ABOUT AN AXIS OFFSET FROMBUT PARALLEL WITH THE AXIS OF ROTATION OF SAID ANVIL MEMBER, CAM MEANSBETWEEN SAID ANVIL MEMBER AND SAID DOG FOR POSITIVELY PIVOTING THE DOGIN THE CLUTCHING DIRECTION, AND A TORSION SPRING EXTENDING AXIALLY OFSAID CLUTCH, SAID TORSION SPRING BEING ROTATABLE WITH SAID HAMMER MASSFOR ENGAGING AND PIVOTING SAID IMPACT DOG IN THE DECLUTCHING DIRECTION.